After a quick Google search of the course, this is what UCAS has to say about their entry requirements for the Level 3 BTEC Sport Diploma at Stationers Crown Woods Academy.
"A minimum grade C in PE GCSE or a Merit in BTEC Sport (First) Diploma."
So as long as you've got one of those, you're good to go!

What you heard about 5 GCSEs is probably to do with A-Level entry requirements, as most colleges require A-Level students to have 5 GCSE grades from A*-C. However as you're doing a BTEC course, that shouldn't matter.

If you have any other questions or want to triple check, I'd contact the school directly. Good luck! :-)